Surface and Catalytic Properties of the CoO/MgO System Doped with FeO
The surface and catalytic properties of pure and Fe 2 O 3 -doped Co 3 O 4 /MgO solids were investigated. The extent of loading was maintained at 38 wt% Co 3 O 4 and the amount of dopant varied between 1.2 wt% and 11.0 wt% Fe 2 O 3 . The pure and doped solids were prepared by calcination at 400–1000°...
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SAGE Publishing
2001-10-01
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| Series: | Adsorption Science & Technology |
| Online Access: | https://doi.org/10.1260/0263617011494448 |
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| author | H.G. El-Shobaky W.M. Shaheen M. Mokhtar |
| author_facet | H.G. El-Shobaky W.M. Shaheen M. Mokhtar |
| author_sort | H.G. El-Shobaky |
| collection | DOAJ |
| description | The surface and catalytic properties of pure and Fe 2 O 3 -doped Co 3 O 4 /MgO solids were investigated. The extent of loading was maintained at 38 wt% Co 3 O 4 and the amount of dopant varied between 1.2 wt% and 11.0 wt% Fe 2 O 3 . The pure and doped solids were prepared by calcination at 400–1000°C of pure and ferric nitrate-treated magnesium carbonate impregnated with cobalt nitrate solution. The samples thus obtained were examined by TG, DTA and XRD methods, nitrogen adsorption studies at −196°C and the catalysis of H 2 O 2 decomposition at 30–50°C. The results revealed that Fe 2 O 3 treatment of the Co 3 O 4 /MgO system followed by calcination at 400°C resulted in an increase in the particle size of the Co 3 O 4 and MgO phases, whilst the opposite effect was observed when the doped solids were calcined at 600°C. Doping of the Co 3 O 4 /MgO system followed by calcination at 400°C effected a measurable decrease in its BET surface area with the reverse effect being observed upon heating at 600°C. An increase in the calcination temperature of pure Co 3 O 4 /MgO up to 800°C brought about an abrupt decrease in the intensity of all the diffraction lines associated with the Co 3 O 4 phase. These disappeared completely upon heating the system at 900°C or 1000°C due to dissolution of the cobalt oxide in the MgO lattice to form a solid solution. A cobalt ferrite phase was detected in the variously doped solids calcined at 800–1000°C even when the initial solids had been treated with 2.4 wt% Fe 2 O 3 . This finding suggests that most of the ferrite phase produced was contained in the outermost surface layers of the treated samples. Treatment of the investigated system with Fe 2 O 3 followed by calcination at 400°C and 800°C led to a progressive decrease in the catalytic activity of the resulting solid due to an increase in the particle size (a decrease in the degree of dispersion) of the catalytically-activeconstituent, i.e. the Co 3 O 4 phase, and due to the conversion of Co 3 O 4 into a CoFe 2 O 4 phase, respectively. In contrast, doping followed by calcination at 600°C led to an increase in the catalytic activity of the resulting solid due to an effective decrease in the particle size of the Co 3 O 4 phase. Calcination of the Fe 2 O 3 -doped system at 400–800°C did not modify the mechanism of the catalyzed reaction but changed the concentration of active sites without changing their energetic nature. |
| format | Article |
| id | doaj-art-cdde35b9bc0045d4b1ea3fb86c523e1e |
| institution | Kabale University |
| issn | 0263-6174 2048-4038 |
| language | English |
| publishDate | 2001-10-01 |
| publisher | SAGE Publishing |
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| series | Adsorption Science & Technology |
| spelling | doaj-art-cdde35b9bc0045d4b1ea3fb86c523e1e2025-01-02T02:58:10ZengSAGE PublishingAdsorption Science & Technology0263-61742048-40382001-10-011910.1260/0263617011494448Surface and Catalytic Properties of the CoO/MgO System Doped with FeOH.G. El-Shobaky0W.M. Shaheen1M. Mokhtar2 Chemistry Department, Faculty of Science, Cairo University, Egypt Physical Chemistry Department, National Research Centre, Dokki, Cairo, Egypt Physical Chemistry Department, National Research Centre, Dokki, Cairo, EgyptThe surface and catalytic properties of pure and Fe 2 O 3 -doped Co 3 O 4 /MgO solids were investigated. The extent of loading was maintained at 38 wt% Co 3 O 4 and the amount of dopant varied between 1.2 wt% and 11.0 wt% Fe 2 O 3 . The pure and doped solids were prepared by calcination at 400–1000°C of pure and ferric nitrate-treated magnesium carbonate impregnated with cobalt nitrate solution. The samples thus obtained were examined by TG, DTA and XRD methods, nitrogen adsorption studies at −196°C and the catalysis of H 2 O 2 decomposition at 30–50°C. The results revealed that Fe 2 O 3 treatment of the Co 3 O 4 /MgO system followed by calcination at 400°C resulted in an increase in the particle size of the Co 3 O 4 and MgO phases, whilst the opposite effect was observed when the doped solids were calcined at 600°C. Doping of the Co 3 O 4 /MgO system followed by calcination at 400°C effected a measurable decrease in its BET surface area with the reverse effect being observed upon heating at 600°C. An increase in the calcination temperature of pure Co 3 O 4 /MgO up to 800°C brought about an abrupt decrease in the intensity of all the diffraction lines associated with the Co 3 O 4 phase. These disappeared completely upon heating the system at 900°C or 1000°C due to dissolution of the cobalt oxide in the MgO lattice to form a solid solution. A cobalt ferrite phase was detected in the variously doped solids calcined at 800–1000°C even when the initial solids had been treated with 2.4 wt% Fe 2 O 3 . This finding suggests that most of the ferrite phase produced was contained in the outermost surface layers of the treated samples. Treatment of the investigated system with Fe 2 O 3 followed by calcination at 400°C and 800°C led to a progressive decrease in the catalytic activity of the resulting solid due to an increase in the particle size (a decrease in the degree of dispersion) of the catalytically-activeconstituent, i.e. the Co 3 O 4 phase, and due to the conversion of Co 3 O 4 into a CoFe 2 O 4 phase, respectively. In contrast, doping followed by calcination at 600°C led to an increase in the catalytic activity of the resulting solid due to an effective decrease in the particle size of the Co 3 O 4 phase. Calcination of the Fe 2 O 3 -doped system at 400–800°C did not modify the mechanism of the catalyzed reaction but changed the concentration of active sites without changing their energetic nature.https://doi.org/10.1260/0263617011494448 |
| spellingShingle | H.G. El-Shobaky W.M. Shaheen M. Mokhtar Surface and Catalytic Properties of the CoO/MgO System Doped with FeO Adsorption Science & Technology |
| title | Surface and Catalytic Properties of the CoO/MgO System Doped with FeO |
| title_full | Surface and Catalytic Properties of the CoO/MgO System Doped with FeO |
| title_fullStr | Surface and Catalytic Properties of the CoO/MgO System Doped with FeO |
| title_full_unstemmed | Surface and Catalytic Properties of the CoO/MgO System Doped with FeO |
| title_short | Surface and Catalytic Properties of the CoO/MgO System Doped with FeO |
| title_sort | surface and catalytic properties of the coo mgo system doped with feo |
| url | https://doi.org/10.1260/0263617011494448 |
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